Ask the Expert: September-October 2002

October 1, 2002

 

Is a low-carbohydrate, high-protein diet both effective and safe?

We recently reported that a low-carbohydrate diet (Atkins-type) works for weight loss, and on average the lipid profiles (one indication of cardiovascular risk) improved over a six-month period. Eighty percent of the subjects [of the study] stayed on the diet, which is remarkable. They lost an average of 10 percent of their original body weight, which is a good amount of weight loss. However, one out of the fifty subjects had an extreme elevation of LDL cholesterol (the "bad" cholesterol) that warranted discontinuation of the diet.

We don't think that there is enough information to recommend this kind of diet yet--not enough is known to be sure that the benefit of weight loss outweighs the risks. A recent eight-week study suggested that kidney stones might develop as a result of this type of diet. They recommended lots of fluid intake to lessen this possibility.

This weight-loss diet, like the others, works because people consume fewer calories than they expend during daily activities. We instructed the subjects to eat fewer than 25 grams of carbohydrate daily. Because we never told these subjects to decrease their calorie intake--but they did anyway--we think that it works by appetite suppression.

As for the low-fat prescription, it is established that some low-fat dieters have a worsening of these same lipid profiles. Maybe there is benefit to both approaches.

Westman is an associate professor in the department of medicine, director of the Durham VA and Duke's Smoking Research Lab, co-director of the Durham VA Stop Smoking Clinic, and an ambulatory-care physician at the Durham VA Medical Center